Log Message:
ruby-gnome: update to 3.4.2.

pkgsrc changes:

- for ruby-gilb2 and ruby-gobject-introspection gems,
  handle generated source files that are no longer included
  in distributed gem files by newly introduced GEM_KEEPBUILD
  variable

Upstream changes (from NEWS):

== Ruby-GNOME 3.4.2: 2020-05-02

This is a follow-up release of 3.4.1.

=== Changes

==== Ruby/GLib2

  * Improvements

    * Add support for Ruby 2.8.

==== Ruby/GTK3

  * Improvements

    * (({Gtk::Widget#style_get_property})): Added a validation.

    * Updated examples.
      [GitHub#1318][GitHub#1319][GitHub#1320][GitHub#1321][GitHub#1322]
      [GitHub#1323][GitHub#1324][GitHub#1325][GitHub#1326][GitHub#1327]
      [GitHub#1328][GitHub#1329][GitHub#1330][GitHub#1331][GitHub#1332]
      [GitHub#1353][GitHub#1354][GitHub#1355][GitHub#1391]
      [Patch by kojix2]

  * Fixes

    * Fixed a typo.
      [GitHub#1307][Patch by Ismail Arilik]

==== Ruby/GObjectIntrospection

  * Improvements

    * Changed to accept (({nil})) as a false value for boolean.
      [GitHub#1305][Reported by Matijs van Zuijlen]

    * Added support for UTF-8 (({GHashTable})) value.

    * Added workaround for (({rsvg_handle_set_stylesheet()})).

  * Fixes

    * Fixed a bug that pointer struct isn't allocated correctly.
      [GitHub#1315][Reported by Konrad Narewski]

==== Ruby/GtkSourceView4

  * Improvements

    * Added support for auto native package install on Ubuntu.
      [GitHub#1309][Patch by Ismail Arilik]

    * Added support for auto native package install on Debian GNU/Linux.

==== Ruby/VTE3

  * Improvements

    * (({Vte::Terminal#spawn})): Made options optional.
      [GitHub#1333][Patch by kojix2]

    * Updated README.
      [GitHub#1335][Patch by kojix2]

==== Ruby/GdkPixbuf2

  * Improvements

    * Updated examples.
      [GitHub#1336][GitHub#1337][GitHub#1338][GitHub#1339][GitHub#1340]
      [GitHub#1341][GitHub#1342][GitHub#1343][GitHub#1344][GitHub#1347]
      [GitHub#1348][GitHub#1349]
      [Patch by kojix2]

    * Updated README.
      [GitHub#1346][Patch by kojix2]

==== Ruby/WebKit2GTK

  * Fixes

    * Fixed dependency check.
      [GitHub#1351][Patch by kojix2]

==== Ruby/RSVG2

  * Improvements

    * Updated examples.
      [GitHub#1357][Patch by kojix2]
      [GitHub#1393][Patch by Jean-Christophe Le Lann]

=== Thanks

  * Matijs van Zuijlen

  * Ismail Arilik

  * Konrad Narewski

  * kojix2

  * Jean-Christophe Le Lann